Oil pickup system for an internal combustion engine, notably a single-cylinder diesel engine

ABSTRACT

The invention describes an oil-pickup system for an internal combustion engine, especially a one-cylinder diesel engine with at least three oil-pickup tubes ( 26, 27, 28 ), which are in communication with the oil pump via a suction tube ( 29 ) and which are disposed in the oil pan ( 24 ) in such a way that, if the internal combustion engine is in inclined position, intake of air is prevented by the control valves associated with the oil-pickup tubes.

The invention relates to an oil-pickup system for an internal combustionengine according to the preamble of claim 1.

An important criterion for the maximum permissible inclination duringoperation of internal combustion engines is the lubricating-oil system.If the inclination of the internal combustion engine exceeds a criticalvalue, it is important to prevent the oil pump from sucking in air andthe propulsion-unit components disposed at the bottom of the crankcasefrom churning in the oil, which would lead to heating of the lubricatingoil and would also hinder the return flow of oil, for example from thevalve-lifter housing to the oil pan. Finally, at steep inclinations, oilcan travel through the crankcase vents into the combustion-air intakesystem, which in the extreme case could cause engine damage in dieselengines because of a speed increase that can no longer be controlled.

Extreme inclinations of internal combustion engines occur, for example,when they are used for motor-vehicle drives. In this area attempts havebeen made to avoid the problems mentioned hereinabove by lowering theoil level by means of a deeper oil pan. It was indeed possible largelyto avoid the cited disadvantages by particularly deep oil pans. Suchspecial oil pans, however, cause high manufacturing costs and limit theuse of the engine because of its greater space requirement.

In a known oil-pickup system (German Laid-open Application DE-OS2339730) of the type mentioned in the introduction, the control valvesare disposed at the inside ends of the respective oil-pickup tubes, orin other words close to the center of the oil pan. The danger thereforeexists that the control valves will respond only after a delay, and sointake of residual air flows has to be tolerated.

The object of the present invention is therefore to provide anoil-pickup system which avoids the foregoing disadvantages and which inparticular responds sufficiently sensitively to avoid intake of airreliably even at steep inclinations.

This object is achieved by an oil-pickup system with the features ofclaim 1. Advantageous embodiments are described in the dependent claims.

According to the invention, the oil-pickup system is provided with atleast three oil-pickup tubes having at least four pickup heads, whichare in communication with the oil pump via a suction tube and which aredisposed in the oil pan in such a way that, when the internal combustionengine is in inclined position, intake of air is prevented by controlvalves disposed in the oil-pickup tubes. Those control valves are openduring “normal” horizontal position of the oil pan. At extremeinclination of the oil pan, however, only the control valves wetted withoil are open. All other control valves remain closed. The oil-pickupsystem according to the present invention can be easily retrofitted toexisting internal combustion engines, since it is merely necessary todetach the oil pan and the normal suction strainer and replace thelatter by the oil-pickup system according to the present invention.Adjustment of the control valves can be accomplished mechanically or byother suitable means.

By the fact that the control valves in the present invention areprovided with valve plates disposed to slide along slide rods under theeffect of gravity and with valve seats disposed at the tube ends, thereis achieved simple but nevertheless sensitively responding mechanicalgravity control of the valves. In addition to the desired automatic openand closed positions of the control valves, depending on inclination,this gravity control also has a “fail-safe” function, since simultaneousclosing of all valves is reliably prevented by the fact that two valveplates are disposed on a common slide rod.

One advantageous embodiment of the invention provides that threeoil-pickup tubes are disposed in the form of an “H”, each of the twoside tubes being provided with two pickup heads. This arrangementensures that sufficient oil to ensure pickup of oil without air ispresent in at least one corner of the oil pan, regardless of tiltposition. The suction tube can be disposed centrally, for example,between the two side tubes, by means of a flange to the connecting tube.

Further advantageous embodiments of the inventive oil-pickup system canbe formed by arranging the oil-pickup tubes in the form of an “X”, “Z”or rectangle. What is important in each case is that at least one pickuphead be present at all corners of the oil pan where the oil level cancollect during inclined positions. Depending on the geometry of the oilpan, this may also be possible, for example, by a triangular, polygonalor star-shaped arrangement of oil-pickup tubes.

A further advantageous embodiment of the present invention provides thatthe pickup heads are provided with a pickup opening directed toward thepan bottom. Without such a structural geometry, a minimum oil levelcorresponding to the size of the tube diameter would have to be presentto avoid intake of air. An even lower oil level is possible only withthe oil-pickup openings disposed at the bottom, as in the advantageousembodiment.

In yet another advantageous embodiment, filter screens are disposed onthe pickup heads. Hereby intake of impurities present in the oil sump isprevented.

A final advantageous embodiment provides that a nonreturn valve isdisposed at the junction between suction tube and oil-pump seat, inorder to prevent the suction-tube and pump spaces from running emptywhen the engine is stopped.

A practical example of the present invention will be describedhereinafter with reference to the attached drawings, wherein:

FIG. 1 shows a schematic top view of an oil-pickup system according tothe present invention in section;

FIG. 2 shows a schematic side view from direction A—A in FIG. 1 insection, the oil pan being in horizontal position, and

FIG. 3 shows a view according to FIG. 2, but with the oil pan tilted.

FIG. 1 illustrates an embodiment of an inventive oil-pickup systemmounted in an oil pan 24. As illustrated, oil pan 24 is disposed ininclined position, and so oil level S1 washes only around pickup head 19of tube 28. The oil-pickup system, which is configured in the form of an“H”, comprises in total three oil-pickup tubes 26, 27, 28, each of whichis provided with a slide rod 1, 2, 3 mounted to slide axially, on thetwo ends of which there are disposed valve plates 4, 5, 6, 7, 8, 9respectively. In the illustrated orientation the valves of oil-pickuptube 27 are open, although they are not wetted by oil. To prevent intakeof air, the valve of tube 26 comprising valve plate 4 and valve seat 30is closed, and the valve disposed at the other end of the slide rod andcomprising valve plate 5 and valve seat 31 is open.

In this arrangement valve rod 1 is mounted to slide axially over axialbearings 10, 11. As already mentioned, oil pickup tube 28 is providedwith the open control valve comprising valve plate 8 and valve seat 34as well as with the closed control valve comprising valve plate 9 andvalve seat 35. The two valve plates 8, 9 are joined by axially slidableslide rod 3, which is mounted movably in bearings 14, 15. The two sidetubes 27, 28 are further provided with filter screens 20, 21, 22, 23.Bearings 12, 13 of slide rod 2 in tube 27 are also illustrated. Valveplates 6, 7 with valve seats 32, 33 are disposed at the ends of sliderod 2.

The oil flow is illustrated in FIG. 1 by arrow 36. Also illustrated inFIG. 1 is outlet opening 29, which is disposed centrally on the top sideof suction tube 26 and is in communication with suction tube 43, notshown, to oil pump 45, also not shown. In the illustrated inclinedposition, valve plates 5 and 8 move under gravity to their openpositions, while valve plates 4 and 9 are shifted by slide rods 1 and 3into their closed positions. Hereby it is ensured that no air is suckedinto the pickup system, which now is open only at pickup head 19. Theposition of the valves in oil-pickup tube 27 is immaterial in theinclined position illustrated in FIG. 1, since tube 27 is completelyisolated from the rest of the oil-pickup system and thus in particularfrom outlet opening 29 by closed valve plate

FIG. 2 schematically shows the oil-pickup system from FIG. 1 in lateralsection, oil pan 24 fastened to crankcase 52 being disposed inhorizontal position, meaning that oil level S2 is parallel to pan bottom40. In this position valve plates 4,5 of tube 26 are both open, or inother words lifted from valve seats 30, 31. Tubes 27 and 28, which arein communication with tube 26 via flange 25, are illustrated in section,as are slide rods 2, 3. Moreover, both valves in both side tubes 27, 28are open, and so oil is being sucked in via all four pickup heads 16,17, 18, 19. Between crankcase 52 and oil pan 24 there is furtherfastened a support plate 41, which has a plurality of openings 42 whichpermit unhindered flow of oil. Plate 41 is provided at the center with asuction tube 43 for an oil-delivery pump 45, which in the diagram is agear pump, the case of which is fastened to plate 41. The oil deliveredby pump 45 to the consuming points of the engine passes into a pressuretube 46. At the lower end, suction tube 43 is constructed as a flange44, which is used for fastening a long, hollow and cylindrical tube 26running parallel to bottom 40 of pan 24. For this purpose tube 26 isprovided with a fastening flange 49. Inside flange 44 there is providedon a pin 50 a tiltable plate valve 51, which bears sealingly on flange49 when the engine is stopped and prevents return flow of oil fromsuction tube 43 and pump 45. A slide rod 1 is mounted to slide parallelto the axis in tube 26. To ensure the necessary smooth travel of rod 1during its sliding movement, there are provided two bearings 10, 11,such as ball bearings, in two perforated transverse flanges 47, 48 oftube 26. Rod 1 carries at one end a plane valve plate 4, 5, whichcooperates respectively with an annular face formed as valve seat 30, 31at the two ends of tube 26.

FIG. 3 shows the oil-pickup system according to FIG. 2, but in tiltedposition, so that oil level S3 is located in the right lower corner.This situation occurs, for example, when a vehicle is climbing a steepslope and oil pan 24 assumes a position inclined at an angle of about⁴⁵E to the horizontal. The oil collects in the right lower corner of oilpan 24, and oil level S3 is again horizontal. Under the effect ofgravity, rod 1 occupies the position illustrated in FIG. 2, in whichvalve plate 5 is moved away from valve seat 31 and the oil supply topump 45 flows through tube 28, which is completely immersed in oil, andpickup heads 18, 19 disposed thereon. Even in this extreme inclinedposition of a vehicle, oil pump 45 and thus also oil pan 24 of theinternal combustion engine can suck in only oil and not any air.

What is claimed is:
 1. An oil-pickup system for an internal combustionengine, especially a one-cylinder diesel engine, which system isprovided with an oil pan and an oil pump, wherein the pickup system isprovided with at least three oil-pickup tubes having at least fourpickup heads, which are in communication with the oil pump via a suctiontube and which are disposed in the oil pan in such a way that, when theinternal combustion engine is in inclined position, intake of air isprevented by control valves disposed in the oil-pickup tubes, andwherein the control valves are actuated by slide rods (1, 2, 3) whichslide under the effect of gravity, characterized in that the controlvalves comprise valve plates (4, 5, 6, 7, 8, 9) which cooperate withvalve seats (30, 31, 32, 33, 34, 35) disposed at the ends of the tubes.2. An oil-pickup system according to claim 1, characterized in thatthree oil-pickup tubes (26, 27, 28) are disposed in the form of an “H”and the two side tubes (27, 28) are each provided with two pickup heads(16, 17, 18, 19).
 3. An oil-pickup system according to claim 1,characterized in that the oil-pickup tubes are disposed in the form ofan “X”, “Z” or rectangle.
 4. An oil-pickup system according to claim 1,characterized in that the pickup heads (16, 17, 18, 19) are providedwith a pickup opening directed toward the pan bottom (40).
 5. Anoil-pickup system according to claim 1, characterized in that filterscreens (20, 21, 22, 23) are disposed on the pickup heads (16, 17, 18,19).
 6. An oil-pickup system according to claim 1, characterized in thata nonreturn valve (29, 51) is disposed between suction tube and oilpump, in order to prevent the suction-tube and pump spaces from runningempty when the engine is stopped.